1. Field of the Invention
The present invention relates to a steering joint device for a vehicle, such as car. Specially, the present invention relates to a steering joint device for coupling a steering device with a steering gear device in a vehicle.
2. Related Background Art
A steering joint device of this kind is adapted to couple a terminal side of a steering shaft to a steering gear device, as disclosed, for example, in Japanese Patent Application Laid-Open No. 61-197820. such steering joint device is provided with an anti-vibration device or vibration prevention device for preventing a vibration which is caused by the tires on a road, a vibration which is caused by an engine suspension, or the like, from being transmitted to the inside of the vehicle through a steering shaft.
An example of the conventional steering joint device will be described below with reference to FIGS. 8 to 10B. Referring to FIG. 8, a steering joint device is comprised of a first universal joint 1 which is fixed to the fore end side of a steering shaft (not shown), a second universal joint 2 which is connected to the steering gear device side, and an anti-vibration device 3 for coupling these two universal joints.
The first universal joint 1 includes a first yoke member 11, a second yoke member 12, and a cross shaft member 13 for coupling the first yoke member 11 with the second yoke member 12.
The first yoke member 11 integrally has a cylindrical portion lla which is fitted on and fixed to the tip end of the steering shaft and a yoke portion 11b which has bifurcated opposed portions. The second yoke member 12 integrally has two side plate portions 12a, 12b which are extended in parallel to face each other, and a bottom plate portion 12c for connecting these side plate portions 12a, 12b.
One shaft 13a of the first cross shaft member 13 is extended perpendicular to the sheet plane of the FIG. 8 and is pivotally supported on the yoke portion 11b of the first yoke member 11 at the two shaft ends thereof, whereas the two shaft ends of the other shaft 13b which is extended at right angles with the former shaft 13a are respectively supported by the two side plate portions 12a, 12b of the second yoke member 12 through bearings 13c, 13d. To this end, the two side plate portions 12a, 12b of the second yoke member 12 are respectively provided with bearing holes 12d, 12e (FIG. 9A) so as to face each other.
On the bottom plate portion 12c of the second yoke member 12, there are formed two holes 12f, 12g on a straight line which makes a right angle with a straight line obtained by projecting the straight line X1--X1 connecting the centers of the bearing holes 12d, 12e onto the bottom plate portion 12c, and which passes a point 0.sub.1 obtained by projecting the middle point of a segment of a line connecting the centers of the bearing holes 12d, 12e onto the bottom plate portion 12c, with this point 0.sub.1 as the middle point therebetween.
On the other hand, a third yoke member 21 of the second universal joint 2 integrally has a cylindrical portion 21a to be fitted on and fixed to an shaft (not shown) on the steering gear side and a yoke portion 21b which has bifurcated opposed portions. A fourth yoke member 22 integrally has side plate portions 22a, 22b which extend in parallel to oppose to each other, and a bottom plate portion 22c connecting these side plate portions 22a, 22b as an integral structure.
One shaft 23a of a second cross shaft member 23 is extended perpendicular to the sheet plane and is pivotally supported on the yoke portion 21b of the third yoke member 21 at the two shaft ends, whereas the both shaft ends of the other shaft 23b which extends perpendicular to the shaft 23a are respectively supported by the two side plate portions 22a, 22b of the fourth yoke member 22 through bearings 23c, 23d.
To this end, the two side plate portions 22a, 22b of the fourth yoke member 22 are respectively provided with bearing holes 22d, 22e (FIG. 9B) to face each other.
The anti-vibration device 3 has a circular anti-vibration rubber 31. This anti-vibration rubber 31 has a rigid structure with internal reinforced fibers. Four through holes for pin insertion are formed through the rubber 31 on crossing lines perpendicular to each other and passing the center of the structure. Only one of the holes is shown in the drawing.
A pair of through holes out of the through holes for pin insertion which face each other in the diameter direction are opposed to the two holes 12f, 12g which are formed on the bottom plate portion 12c of the first yoke member 12 of the first universal joint 1, and pins 32a, 32b are inserted through these corresponding holes 12f, 12g. A structure for connecting the pins 32a, 32b with the bottom plate portion 12c and the anti-vibration rubber 31 is the same as a structure for connecting the anti-vibration rubber 31 with an oval flange portion 33a of a lower shaft 33, the structure of which will be described later. The latter is shown in the drawing and will be fully described.
More specifically, holes for pin insertion are formed through the oval flange 33a of the lower shaft 33 to face the two remaining through holes of the anti-vibration rubber 31, and pins 34a, 34b are inserted through these holes, respectively. FIG. 8 shows a cross section of a part of the pin 34a out of the two pins 34a, 34b. The pin 34a is inserted through a hole of the anti-vibration rubber 31 through a bush 35. A stopper 36 made of a metallic plate is interposed between an enlarged end portion 34c of the pin 34a and the anti-vibration rubber 31, and the pin 34a is caulked onto the oval flange 33a at the opposite end portion to connect the anti-vibration rubber 31 to the oval flange portion 33a. The bush 35 is provided to surround the pin 34a from the stopper 36 to the oval flange 33a. The stopper 36 is extended as if striding over the pins 32a, 32b described above which are adapted to connect the bottom plate portion 12c of the second yoke member 12 of the first universal joint 1 to the anti-vibration device 3, so as to form a predetermined space between the stopper 36 and the outer periphery of the pin 32a or 32b.
The bottom plate portion 12c of the second yoke member 12 and the anti-vibration rubber 31, and the anti-vibration rubber 31 and the oval flange 33a of the lower shaft are respectively connected by the pins in the above-mentioned manner. Thus, a torque is transmitted through the anti-vibration rubber 31 with respect to a normal torque load. However, when the torque load exceeds a predetermined value, the stopper 36 starts to function.
Generally, in the steering joint device, it is required to dispose the first universal joint 1 and the second universal joint 2 with an optimal phase angle therebetween in accordance with a state of the used space. This phase angle is an angle made by the first cross shaft member 13 and the second cross shaft member 23, which is an angle made by the first yoke member 11 and the third yoke member 21. This is at the same time an angle .theta.' which is made by the above-mentioned straight line X1--X1, and a line Y1--Y1 connecting the centers of holes 22d, 22e. A setting of this phase angle was conventionally adjusted when the lower shaft 33 is secured to the bottom plate portion 22c of the second yoke member 22 of the second universal joint 2 by welding, or the like.
This phase setting has also been conducted by serration connection or by using a yoke integrally forged, instead of by welding.
However, there may be spatial limitations depending on the geometry of the vehicles, and it may be difficult or impossible to set a desired phase angle by these conventional methods.